The present invention relates to a bit synchronization circuit for regenerating clock signals which are synchronized to a received digital signal and, more particularly, to a bit synchronization circuit for regenerating such a clock signal by variable frequency division of an original clock signal and synchronizing the clock signal to the received digital signal.
A bit synchronization circuit of this type, in the prior art, generates a synchronized clock by extracting the transition point of the received digital signal. The frequency division ratio of a variable frequency divider is increased or decreased so as to synchronize the transition point of the digital signal and the trailing edge (or leading edge) of the regenerated synchronized clock with one another. The control of the variable frequency divider is effected for each bit of the received digital signal.
In the bit synchronization circuit of the prior art, because it operates for each bit of the received digital signal, the lead time and delay of the regenerated clock signal are alternately detected on a bit-by-bit basis if the duty cycle ratio of the received digital signal deviates from a balanced value of 50 percent. Therefore, the phase of the regenerated clock signal is not properly adjusted while the frequency division ratio of the frequency divider is changed on the basis of the detected information.